The present invention relates to providing power and, more specifically, to providing a compact, high-voltage, high-frequency transformer to provide power.
Power converters are used to convert power from an input to a needed power for provision to a load. One type of power converter is a transformer. Transformers may be designed to convert a fixed AC input voltage into a higher or lower AC voltage. The architecture chosen may provide for high frequency operation, pulse-width-modulation, isolation, and the like.
Different types of transformers may be used depending on a particular application. A typical power transformer includes one or more input windings and one or more output windings. The input and output windings are both wrapped around a core formed of a magnetic material. An alternating current provided at the input (e.g., primary) windings causes a varying magnetic flux in the transformer core. This flux leads to a time varying magnetic field that includes a voltage in the output (e.g., secondary) windings of the transformer.
In some cases, the core is so-called “closed-core.” An example of closed-core is a “shell form” core. In a shell form, the primary and secondary windings are both wrapped around a central core arm and a both surrounded by outer arms. In some cases, more than one primary winding is provided and multiple secondary windings may also be provided. In such systems, based on the input and to which of the primary windings that input is provided (of course, power could also be provided to more than one primary winding in some instances) different output voltages can be created at each of the secondary windings.
Some power transformers operate at high voltages and/or currents. Such power transformers may produce strong electromagnetic (EM) fields. One approach to deal with the electric fields and parasitic currents they produce is to shield one or both of the primary and secondary windings. This may be especially important where the power transformer operates in high, very-high or ultra-high frequency bands. An example is a power transformer used in a microwave power module.
In some applications, the cost of high frequency and/or high voltage transformers for use in compact equipment can be high relative to the cost of the equipment as a whole or compared to other elements in the equipment. Further, in some cases, the transformer can be difficult to make or prone to failures.